The invention relates to a valve arrangement with pressure regulation and pressure regulation.
The pump supplies, for example, the gear system of a motor vehicle, particularly a revolutions-torque converter, and automatic or CVT gear system and/or a power steering system. The stream of liquid supplied to the consumer must be set to a certain amount. To this ends the main stage, the flow regulator valve, is used. The pressure limiting valve, which is also described as a pressure pilot, is used to set the maximum pressure of the medium supplied from the pump. It has emerged that the construction of the valve arrangement is, in many cases, costly and space-intensive. Often, different demands are made of the spatial arrangement of the pressure and suction connections of a pump containing a valve arrangement of the type discussed here. There are, for example in automatic gear system, tight spatial relations and/or there are mounting positions which are difficult to access. In addition, the connections and the main oil flow mechanism are pre-set in many cases. Moreover, in automatic gear systems, the valves are some distance away from the pump, meaning that the charging of the pump is poor, and the proportion of air in the oil is also large.
Therefore the aim of the invention is to create a valve arrangement of the type named at the beginning which does not exhibit these disadvantages.
In order to resolve this problem, a valve arrangement is proposed. The valve arrangement is characterized in that the flow regulator has a flow regulator piston with an initial hydraulic resistor which has a split pressure return surface. The first part of the surface of the pressure return surface is impacted with a pressure p1, and the second with the pressure p2. The split pressure return surface allows the mail oil flow through the flow regulator valve and also gives it a pressure limiting function, which would preferably be as a result of the pressure p2. This not only simplifies the guiding of the flow of medium, but also reduces the size of the pressure limiting valve. This means that the valve arrangement and a pump can be arranged within a single casing in confined spaces.
In order to resolve this problem, a valve arrangement is proposed which demonstrates the features named in claim 1. The valve arrangement is characterised in that the flow regulator valve has a flow regulator piston with an initial hydraulic resistor which has a split pressure return surface. The first part of the surface of the pressure return surface is impacted With a pressure p1, and the second with the pressure p2. The split pressure return surface allows the main oil flow to flow through the flow regulator valve and also gives it a pressure limiting function, which would preferably be as a result of the pressure p2. This not only simplifies the guiding of the flow of medium, but also reduces the size of the pressure limiting valve. This means that the valve arrangement and a pump can be arranged within a single casing in confined spaces.
An embodiment of the valve arrangement is preferred which is characterised in that the two parts of the surface of the pressure return surface are separated by a second hydraulic resistor, which can be arranged after the first hydraulic resistorxe2x80x94in the direction of flow and integrated into the flow regulator piston. Alternatively, the second hydraulic resistor can also be within the casing. This means that the structure is very compact and the guiding of the medium within the pump is simplified. In the preferred embodiment, the hydraulic resistors take the form of baffles.
In a particularly preferred example embodiment of the valve arrangement, the clutch mechanism takes the form of a plug which is inserted into a socket in the gear system. Preferably it is ensured that the clutch mechanism, i.e. the plug and the socket, is cylindrical in form. In particular, it is ensured that the outer diameter of the plug is chosen so that it is only very slightly less than the internal diameter of the socket, which means that the valve arrangement or the pump can be positioned particularly simply and precisely in relation to the great system.
A particularly preferred embodiment is characterised in that the sleeve surface of the cylindrical plug and/or the inner walls of the socket has/have a circular seal. This means that a seal can be achieved which is independent of the external characteristics of the housing of the valve arrangement or the pump and the housing or the flange of the gear system. There fore the seal of the connection between the valve arrangement and the gear system is independent of the size of the gap between the flange of the gear system and the housing of the valve arrangement.
The invention also relates to a pump for a gear system, particularly an automatic gear system, where the pump, a great control system, as revolutions/torque conversion unit and a valve for limiting the volume flow and/or limiting pressure and/or pressure modulation of the system pressure of the working medium of the great system are arranged within a common gear system casing. According to claim 24, the invention provides the valve allocated to the pump, specifically integrated within the casing of the pump. This is advantageous inasmuch as the particularly close arrangement between the pump and the valve allows short connections between these two components, which means that high volume flows can be supplied in the pump with a low level of loss. Oil flowing from the valve mechanism can also be used to charge the pump better, as the oil is returned directly via short routes.
For example, a flow regulator valve to limit flow volume and/or a pressure limiting or safety valve to limit pressure and/or a main pressure valve to modulate pressure can be used as the valve which is allocated to the pump. This valve or valves can also be externally influenced by an active component. What is known as a proportional valve should be mentioned specifically here, this can provide a modulated pre-control pressure for the valve, so that what is known as a pre-control circuit is formed. Alternatively, it can also be arranged so that the valve can be influenced by a magnet, a spring or any number of pressures present in the hydraulic system. This means that the line of the flow volume course can be set to be adjusted or influenced according to the operational status of the gear system.
Particularly preferred is an example embodiment of the gear pump where the valve arrangement in accordance with one or more of claims 1 to 22 is used for the valve. Alternatively or additionally, what is known as a main pressure valve can be used.
In a particularly preferred embodiment, the gear pump takes the form of a wing cell pump or a roller cell pump, which is at least one strike, i.e. has one suction chamber and one pressure chamber each. This type of wing cell pump and roller cell pump is characterised by a stroke ring which influences the inward and outward motion of the wings or rollers. At least one suction channel of the pump is adjacent to a hollow in the stroke ring, so that the cross section of the suction channel is extended. This is a simple way of ensuring that the suction resistance for the working medium is reduced, so that there are slight low pressures in the pump area.
Particularly preferred is an embodiment where the hollow is open at the edges and where the open side is arranged opposite a suction pocket which can be formed, for example, in what is known as a pressure plate. Therefore the mouth of the hollow is in a lateral surface of the stroke ring, meaning that the cross section of the suction channel in the area of the suction pocket and the hollow is increased.
In a particularly preferred embodiment, the hollow which is open at the sides has a rounded section on at least one of the areas between its mouth and its limiting walls at the sides. Preferably, the area between the mouth and a side wall which lies within the large circle of the stroke ring should be chosen. It is particularly advantageous ifxe2x80x94going from the mouth towards the side wallxe2x80x94there are two cut-out sections, so that the mouth continually climbs into the first section via an area, in order then to pass into a smaller rounded section. The transfer areas formed in accordance with the invention do not have any major influence on the stability of the stroke ring itself, as the notching effect is low here.